Method of sealing blister type packages



Sept. 24, 1963 H. A. ROHDIN METHOD OF SEALING BLISTER TYPE PACKAGES Filed Oct. 26, 1960 INVEN TOR. HOWARD A. ROH IN ATTORNEY blister.

United States Patent i a? ForestAve., Gienltidge, NJ.

on. 26, was, Ser. No. 65,189 2 cream. or. 53-42 It is an object of this invention to provide an improved method of sealing blister type packages of particular advantage where the contents is a perishable food-stuff.

The above and other objects will be made clear from the following detailed description taken in connection with the annexed drawings in which:

FTGURE 1 is a section through the dies for distorting and sealing the package;

FlGURE 2 is a View similar to FIGURE 1, showing a package and its lid in place; and

FIGURE 3 is a side elevation of the complete package.

in packaging perishable food products in transparent, thermoplastic blisters, for merchandising appeal, it is most desirable that the package appear absolutely full. This raises the problem, however, of possible contamination of the usual scalable flange around the mouth of the Such contamination may interfere with the efiicacy of the seal, when the lid is applied. Worse yet, contamination may extend outside the area of the seal, with the result that the package may have spoiled foodstuif in its margin. Even with the closest, hence most costly inspection, such packages may reach the consumer, with consequent loss of good will.

The present invention provides a solution to the foregoing problem by creating, at the time of filling a distortion of the blister to increase its intended capacity. The blister then is filled to a level below that of the flange, thereby avoiding the possibility of contamination on the flange. The lid is then heat sealed to the flange and the distortion is removed to bring the package to full condition.

Referring now to FIGURE 1, there is shown a female die 18 having a package receiving pocket 12, the bottom of which has a sunken portion 14. At the top, adjacent the pocket 12 and surrounding the same is a pressure supporting surface 16. The pocket, except for the sunken portion 14 is the shape of the blister portion of the ultimate package. A heated die 18, conforming in shape to the surface 16 is movable toward and from that surface by conventional means. A duct 20 is formed in the base of the die and communicates with the sunken portion 114.

In FIGURE 2 a blister 22 has been placed in the pocket 12. The blister has the usual peripheral flange 24. Vacuum is pulled through the duct to draw the normally flat bottom of the blister 22 into the sunken portion 14, thereby temporarily increasing the capacity of the blister. The blister is then filled to a level indicated by the line 26, the quantity of contents of the blister being that normally required to fill the blister to the level of the flange 24. A lid 28 is then placed over the flange 24, and the die 18 is lowered to form a heat seal Patented Sept. 2%., 1963 between the lid 28 and the flange 24. The vacuum is then released through the duct 28, whereupon the bottom 38 or" the blister springs back to flattened condition on the line 32. It will be understood that the die 18 is not needed, and in any material capable of forming a selfsustaining blister, there will be no permanent set induced by the drawing of the bottom into the sunken portion 14.

FTGURE 3 shows the final package. Depending on the ma.erial used, there may be a slight upward bulge of the lid 28 to approximately the line 3 2-. Where such a bulge is objectionabie the sealing may be done under vacuum. It is also possible, and sometimes may be desirable to use a lid of material which will pass a particular gas, such, for example, as carbon dioxide, and then to fill the space above the line 26 with such gas to displace the air which otherwise would be present. After the seal is made, and the vacuum released, the gas'will pass through the lid 23, which will then return to flat tened condition. Examples of such materials are polyethylene and most of the vinyl films.

it will be apparent that filling can be done through the heated die 18, and the lid 28 may be drawn over the blister 22, between the die 18 and the surf-ace 16. it will also be apparent that strips, or even entire sheets of blisters may be filled and sealed simultaneously, and such is entirely within the purview of this invention.

I claim:

1. A method of filling and sealing blister-type packages comprising: providing a die of the same shape as a blister to be filled, but of greater volume; placing a prefor-med, selfsustaining blister in said die; evacuating said die to draw said blister into conformity therewith; filling said blister with contents equal to its normal volume; lling the space above said contents with an inert gas; sealing a lid pervious to such gas on said blister and releasing the evacuation of said die.

2. A method of filling and sealing blister-type packages comprising: providing a blister, preformed of plastic material to its normal size and shape, said blister being self sustaining and of limited flexibility; distorting said blister to increase its internal volume; filling said blister with contents equal to the normal internal volume of the blister; thereafter filling an inert gas into the blister; sealing a lid on said blister, said lid being permeable to such gas, and restoring the blister to substantially its internal volume.

References Cited in the file of this patent UNITED STATES PATENTS 1,693,262 7 Taylor Nov. 27, 1928 2,293,142 Johnson Aug. 18, 1942 2,335,738 Casey Nov. 30, 1943 2,418,142 Socke Apr. 1, 1947 2,878,154 Cheney et al. Mar. 17, 1959 2,878,630 Strin et al Mar. 24, 1959 2,879,635 Brock Mar. 31, 1959 2,888,787 Cloud June 2, 1959 

1. A METHOD OF FILLING AND SEALING BLISTER-TYPE PACKAGES COMPRISING: PROVIDING A DIE OF THE SAME SHAPE AS A BLISTER TO BE FILLED, BUT OF GREATER VOLUME; PLACING A PREFORMED, SELFSUSTAINING BLISTER IN SAID DIE; EVACUATING SAID DIE TO DRAW SAID BLISTER INTO CONFORMITY THEREWITH; FILLING SAID BLISTER WITH CONTENTS EQUAL TO ITS NORMAL VOLUME; FILLING THE SPACE ABOVE SAID CONTENTS WITH AN INERT GAS; SEALING A LID PERVIOUS TO SUCH GAS ON SAID BLISTER AND RELEASING THE EVACUATION OF SAID DIE. 